Skip to content
RADON411

Locations and reports

Radon Levels in Montgomery County, Tennessee

EPA puts Montgomery County in Zone 2, its middle radon zone, and only 10 radon tests from it are on file with CDC (2023). Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    33.8%

    0.5 pts above TN

    Montgomery
    33.8%
    Tennessee
    33.3%

    597 tests, 2008 to 2017

  • Median result

    2.3pCi/L

    Below action level

    Montgomery
    2.3 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    597

    12th of 80 by tests

    Montgomery
    597
    Davidson
    5,592

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    EPA predicts 2 to 4 pCi/L indoors

  • Rank in Tennessee

    35 of 80

    Middle half

    Montgomery
    33.8%
    Jefferson
    56.8%

    By share, of 80 with 30+ tests

Read a result for Montgomery County

Starts at Montgomery County's median, 2.3 pCi/L

2.3pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 2.3 pCi/L

Between 2 and 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 4 and aboveEPA says fix it

This result is between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Montgomery County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Montgomery County, At a glance

Montgomery County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Montgomery County is a county: EPA's forecast for it as a whole is an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³). It describes no single address, and homes above EPA's are found in every zone, this one included.

USGS geologic potential: Moderate across 95% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Montgomery County, 2023

Share of reported tests at or above 4 pCi/L, by year, Montgomery County
Share of reported tests at or above 4 pCi/L, by year, Montgomery County
YearShare of reported tests at or above 4 pCi/L
202221.7%
202340.0%

2023: 40.0%. Across these years the share ran from 21.7% to 40.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 10 tests were reported to CDC for Montgomery County over 2023, and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.

Measured: CDC tracking data. Figure above: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).

How to read these figures

Montgomery County, Compared

Montgomery County radon figures, compared

Calculated by Radon411

In Montgomery County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (202 of 597) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 1.9 points lower. Across 95 Tennessee counties pooled together, 33.3% of tests reached that level, so Montgomery County runs 0.5 points above its state.

The newest figure, in 2023, counts only 10 tests (40.0% at or above 4 pCi/L), too few to compare, so this reading uses the 597-test figure.

Of 6 neighbours with a figure, 2 reported a larger share at or above 4 pCi/L and 4 a smaller one; the spread is 17.7% (Todd County, KY) to 36.1% (Christian County, KY). By share, Montgomery County is 35th of 80 Tennessee counties with 30 or more tests for the same period.

Half the tests came in under 2.3 pCi/L and half over it; the single highest reached 79.2 pCi/L. Below the action level, 274 tests (45.9%) came in under 2 pCi/L, against 42.4% statewide, and 121 tests (20.3%) fell between 2 and 4, against 24.3% statewide.

Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 33.8% share point the same way here. USGS geology rates 95% of the county's land moderate radon potential. CDC also counts 15 tests taken after mitigation in Montgomery County for the same period: tests in homes where a fix was already in.

The busiest year on file was 2022, with 138 tests reported; the quietest, 2023, had 10.

Montgomery County against Tennessee, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Montgomery County
Montgomery County59733.8%2.3 pCi/LThis county
Tennessee, pooled95 counties, pooled31,06633.3%Not pooled−0.5 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+1.9 points
Jefferson Countyhighest in the state14656.8%4.7 pCi/L+23.0 points
Chester Countylowest in the state440.0%1.1 pCi/L−33.8 points
Christian County, KYborders it7236.1%3.2 pCi/L+2.3 points
Cheatham County, TNborders it20534.1%2.3 pCi/L+0.3 points
Robertson County, TNborders it27328.9%1.9 pCi/L−4.9 points
Houston County, TNborders it1428.6%2.8 pCi/L−5.2 points
Dickson County, TNborders it20926.3%2.1 pCi/L−7.5 points
Stewart County, TNborders it9526.3%2.1 pCi/L−7.5 points
Todd County, KYborders it6217.7%1.8 pCi/L−16.1 points
Where Montgomery County's reported results fell, 2008 to 2017, laboratory, beside Tennessee and the United States
ResultMontgomery County testsMontgomery County shareTennessee shareU.S. shareAgainst Tennessee
Under 2 pCi/L27445.9%42.4%39.6%+3.5 points
2 to 4 pCi/L12120.3%24.3%24.7%−4.0 points
4 pCi/L and above20233.8%33.3%35.7%+0.5 points
Montgomery County ranked among the 80 Tennessee counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Hickman County30 of 8012035.0%2.2 pCi/L
Clay County31 of 804634.8%2.3 pCi/L
Johnson County32 of 8015734.4%2.3 pCi/L
Cheatham County33 of 8020534.1%2.3 pCi/L
McMinn County34 of 8010634.0%2.8 pCi/L
Montgomery County35 of 8059733.8%2.3 pCi/L
Roane County36 of 8025833.7%2.5 pCi/L
Knox County37 of 802,45233.6%2.5 pCi/L
Benton County38 of 803033.3%2.0 pCi/L
Perry County39 of 804032.5%2.0 pCi/L
DeKalb County40 of 805930.5%3.1 pCi/L
Montgomery County radon tests by year, against Tennessee's pooled share
YearTestsAt or above 4 pCi/LMedianHighestTennessee, pooledChange from the row before
20231040.0%2.0 pCi/L19.6 pCi/L24.9%+18.3 points
202213821.7%1.6 pCi/L9.4 pCi/L23.8%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Montgomery County, Geology

The ground under Montgomery County

Predicted

Most of the ground under Montgomery County is one class on USGS's geologic map: 94.9% of its land is moderate radon potential, with 5.1% high. The map puts 94.9% of Montgomery County in the area it calls Highland Rim and 5.1% in Cherty Highland. USGS gives the first a radon index of 11, in the moderate band (9 to 11), and the second 12, in the high band (12 to 17).

USGS's geologic areas under Montgomery County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Highland RimPaleozoic sedimentary rocks (limestone, shale, chert, and dolostone).Moderate1194.9%
Cherty HighlandCherty dolostone.High125.1%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Montgomery County beside the ground around it

Tennessee as a whole has more high-potential ground than Montgomery County: 47.2% of its land, against 5.1% here. Of the 7 counties that border it, 4 have more high-potential ground, Cheatham County the most at 79.0%.

Share of land by USGS radon potential: Montgomery County, the 7 counties bordering it and Tennessee
AreaEPA zoneLow potentialModerate potentialHigh potential
Montgomery CountyZone 2None94.9%5.1%
Cheatham CountyZone 2None21.0%79.0%
Dickson CountyZone 2None73.2%26.8%
Houston CountyZone 2None78.5%21.5%
Todd County, KYZone 2None100%None
Stewart CountyZone 2None82.7%17.3%
Robertson CountyZone 2None96.6%3.4%
Christian County, KYZone 2None100%None
Tennessee95 counties, pooled by land areaVaries30.5%22.3%47.2%

The map rates the ground, not the air in any home.

Local help

Montgomery County, Local resources

Radon testing and mitigation in Montgomery County

What Tennessee's program says
Phone
1-800-232-1139
Email
TDEC.Radon@tn.gov

What it means

Montgomery County, Questions

Questions about radon in Montgomery County

Are radon levels high in Montgomery County?

In 2023, 40.0% of the radon tests reported to CDC for Montgomery County, Tennessee were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.0 pCi/L. Of 80 Tennessee counties with 30 or more tests for the same period, 34 reported a higher share; pooled, the state comes to 33.3%.

Which counties border Montgomery County?

Montgomery County borders 7 counties: Cheatham County, TN, Dickson County, TN, Houston County, TN, Todd County, KY, Stewart County, TN, Robertson County, TN and Christian County, KY.

Products

Montgomery County, Products

Testing a home in Montgomery County

In Montgomery County, 33.8% of 597 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 33.3% pooled across Tennessee. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Montgomery County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Montgomery County homes, compared

Explore

Montgomery County, Bordering counties

Counties bordering Montgomery County

Calculated by Radon411

Montgomery County, Cities and towns

Cities and towns in Montgomery County

Montgomery County is growing: the Census Bureau puts it at 249,935 residents on July 1, 2025, up 12.9% from 221,286 in 2020. That works out to 464 people per square mile of land. Clarksville, its one incorporated place, has 188,829 residents, 75.6% of the total. Reported testing is thin here: 597 tests over 2008 to 2017, or 2.4 for every 1,000 residents (2025 estimate), where Tennessee as a whole comes to 4.2.

Clarksville is the one incorporated place here; CDC publishes no figure by town, so it reads Montgomery County's.

Clarksville, Montgomery County: residents on July 1, 2025
PlaceResidentsSince 2020Share of residents
Clarksville188,829+12.7%75.6%

One incorporated place, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025).

Montgomery County, Homes

Homes in Montgomery County

Of Montgomery County's 90,226 homes, 72% are detached houses, against 68% across Tennessee; 12% are in buildings of five or more homes. Much of Montgomery County is recent building: 44% of its homes have gone up since 2000 and the middle year built is 1997, against 1986 for Tennessee. 63% of occupied homes are lived in by their owner (Tennessee: 67%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Montgomery County, Tennessee, 2019 to 2023
HomesMontgomery CountyTennessee
Housing units90,2263,095,472
Detached houses72%68%
In buildings of 5 or more12%14%
Mobile homes4%8%
Built before 19608%18%
Built since 200044%29%
Middle year built19971986
Owner-occupied63%67%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.